1. Field of the Invention
The invention relates to a panel, especially a floor panel, with a core of wood product or wood product-plastic mixture, a top and a bottom which is provided with hook elements which correspond to one another on at least two opposite side edges, the first hook element being formed by profiling which is essentially open to the top and the second hook element being formed by profiling which is essentially open to the bottom and which on the first hook element forms a projection which is pointed essentially toward the top and on the second element a projection pointed essentially toward the bottom, and at least one of the hook elements being a spring element which deviates in the horizontal direction in the joining motion and then for purposes of vertical interlocking snaps in behind an interlocking edge which extends essentially in the horizontal direction, and at least one of the hook elements being segmented and a plurality of spring elements spaced parallel forming in this way.
2. Discussion of Background Information
This panel is known for example from DE 10 2007 020 271 A1.
In the panels known from DE 10 2007 015 048 A1 the interlocking element which has an interlocking surface which extends in the horizontal direction is cut free relative to the core, by which the interlocking element can execute a deviating motion in the lowering motion. At a small panel thickness, especially for panels with a thickness of 6 or 7 mm, the stiffness of these connections is often not sufficient. In conventional tests with steel rolls (DIN 13329) slight vertical offsets between adjacent panels can arise due to multiple cyclic loading, especially in the region of the transverse-side interlocking; this becomes immediately apparent with unfavorable light incidence, by which the floor coating can engender the impression of poor quality.
DE 102 24 540 A1 discloses a floor panel which is bordered in the horizontal plane by a top which is provided with a decorative layer and a bottom which is provided for support on a subfloor, which panel is provided with means for detachable connection of at least two panels, on at least one first side edge the connecting means being made such that interlocking takes place in the transverse direction and vertical direction, on a second side edge which runs at an angle to the first side edge interlocking elements being made for interlocking in the vertical direction with other panels. In this floor panel the interlocking elements are made spaced apart from one another in the transverse direction and in the vertical direction on two essentially vertically aligned walls which are spaced apart. So that joining of two panels remains possible, the horizontally aligned interlocking surfaces can be dimensioned to be very small. The transverse extension is in the range of roughly 0.05 to 1.0 mm. But this necessarily also makes it possible to accommodate small, vertically directed forces so that fabrication with extremely small tolerances is necessary in order to ensure that the connection does not snap back under normal loading with slight floor unevenness and/or soft subsurfaces.
DE 101 59 284 A1 discloses a floor panel with a core of wood product which has a groove which forms an upper lip and a lower lip on at least one side edge over its length and on the opposite side edge is made with a tongue which corresponds to the groove. For interlocking of panels which are connected to one another the tongue is provided with at least one projection, and the groove has at least one depression on the lip which is opposite at least one projection. Here the depression is longer than the projection, and the lip provided with the depression on the side edge has at least one recess which extends as far as the depression, the length of the recess being at least as large as the length of the projection. Relative to the lengthwise direction the recesses and the projection are offset to one another. The connection of two panels takes place by this configuration in the manner of a quarter-turn fastener by first of all a joining movement which points in the transverse direction of the panel being carried out so that the tongue is inserted into the groove and then the interlocking of the two panels takes place in the manner of a quarter-turn fastener by a movement pointed in the lengthwise direction.
This profiling of the side edges is mechanically very complex and installation of the panels becomes in part more complicated since it must be ensured that the tongues are plunged into the grooves over the full length of the side edges. If then the concluding interlocking motion is not carried out completely parallel to the lengthwise axis of the panel, there is the danger that the panel to be interlocked will be tilted and will swivel the tongue out of the groove so that interlocking is no longer possible.
DE 198 23 357 A1 discloses a wall tile with an essentially flat, cuboidal base body which has a visible surface, a fastening surface and face surfaces which connect the visible surface to the attachment surface. On at least one of the face sides there is a spacer which is integrated with the tile and which comprises means for compensation of the thermal elongation of the tile. These spacers are profiled in a hook shape so that two tiles can be connected to one another by way of a vertical lowering motion.
DE 200 08 708 U1 discloses panels with side edges which are profiled in a hook shape and which can be connected positively to one another by a vertical lowering motion.
WO 2008/116623 A1 discloses floor panels which on at least two opposite side edges have profiling corresponding to one another such that two identically made panels can be connected and interlocked with one another by an essentially vertical joining movement in the horizontal and vertical direction. The interlocking in the vertical direction is caused by a spring element which can be moved in the horizontal direction and which snaps in behind an interlocking edge which extends essentially in the horizontal direction in the joining motion. This spring element is formed integrally out of the core.